This invention relates to a flame cutting machine with lost cut re-establishment.
Flame cutting machines having a plurality of torches for cutting a plurality of rows of pieces in succession from a flat metal plate-like workpiece have long been known. It has also been known for some time to utilize a Computerized Numerical Control (CNC) having a programmable memory for automatically operating such machines.
Problems occasionally arise during flame cutting of a row of pieces in that one or more of the cutting flames may stop cutting at some point along the path of travel of one or more of the torches. If the cycle is completed for that row, the pieces adjacent flames which did not stop cutting will be properly cut, while the cut of pieces where the flame stopped cutting will be lost so that they are not completed. A defective row is thus created.
It has previously been known to reverse the row cutting cycle to place the torches at the point of beginning of the lost cut, re-adjust the adjacent torches and then re-run the remainder of the cycle so as to pick-up the lost cut on any affected piece.
There are numerous reasons for losing a cut. One of the primary reasons is that, at some point the workpiece becomes insulated from the heat of the flame and flowing oxygen. This may be due to surface conditions of the metal which may have rust or mill-scale thereon at scattered locations. Another reason is the occasional improper setting of the torch height or heat output, either by the operator or by the CNC itself.
It has been observed that a high percentage of lost cuts commence at or closely adjacent the start-pierce point for cutting, which is positioned on a lead-in line for the piece to be cut. This is usually due to the above-mentioned improper setting so that the flame does not provide the initial pierce of the workpiece at the start-pierce point.
In the type of flame cutting operation under consideration here, the row cutting cycle usually terminates a short distance, for example 1/2", from the start-pierce point on the lead-in line. To reverse the cutting cycle so that all the torches traverse their complete cutting paths from the cut termination point back to at or adjacent the start-pierce point in order to pick up a lost cut is undesirable, especially from the standpoint of time used.
It is a task of the present invention to provide a flame cutting machine of the type described above which gives the operator the capability of doing more than reversing the row cutting cycle for lost cut reestablishment.
It is a further task of the invention to give the operator the option of moving the torches directly from the cut termination point to the nearby start-pierce point, which is apt to be adjacent the lost cut, for repeating at least a part of the previous cutting cycle in the same row.
In accordance with various aspects of the invention, a flame cutting machine is provided having a CNC control with a programmable memory wherein the memory is programmed to cause automatic cutting of rows of pieces continuously in succession, and wherein the memory also includes selectively actuatable instructions to prevent the torches disposed at a termination point from automatically proceeding to the next row, but instead to cause the torches to automatically proceed directly to the start-pierce point of the row just completed. The torch or torches which have properly cut a complete piece are turned off, while the remaining torch or torches which have involved a lost cut are re-activated at the start-pierce point so, as the row cutting cycle is repeated, the previously lost portions will now be cut. The memory is also programmed to selectively instruct the machine to reverse from the cut-termination point, if desired.